SMD-type 660 nm wavelength semiconductor laser diode device is fabricated using silicon resin molding technology and fabricated a BT resin printed circuit board. BT resin electrode structure printed circuit boards with soldering electrode pads and through holes for heat dissipation were fabricated. The SMD process is an injection molding technique in which the chip is molded from silicon material and then cut by a dicing process to complete the beam emission surface. The fabricated SMD-type semiconductor laser diode exhibits a good near-field beam pattern with no scattering/dispersion caused by the printed circuit board or silicon molding in the emitted laser beam, or reflections around the chip. It was also confirmed that the heat generated at 20 mA operation has good heat dissipation characteristics through the through-hole heat dissipation structure.

Citations

• Mitigating Contact‐Constricted Thermal Bottlenecks by Magnetically Programmable hBN Bridge Fillers in Al2O3/Epoxy Composites
  Yeonwook Jeong, Sabina Ghorsaine, Chan‐Jae Lee, In Kim, Mooho Lee, Hyejeong Lee, Ginam Kim, Jong‐Woong Kim
  Small.2026;[Epub]     CrossRef

Cast-resin transformers are widely installed in various electrical power systems because of their low operating cost and low influence on external environmental factors. However, when they have an internal defect during the manufacturing process or operation, a partial discharge (PD) occurs, and eventually destroys the insulation. In this paper, a Rogowski-type PD sensor was studied to replace commercial PD sensors used for the insulation diagnosis of power apparatus. The proposed PD sensor was manufactured with four different types of PCB-based winding structures, and it was analyzed in terms of the detection characteristics for standard calibration pulses and the changes of the output voltage according to the distance. The output increased linearly in accordance with the applied discharge amount. It was confirmed that the hexagon structure sensor had the highest sensitivity, because the winding cross-sectional area of the sensor was larger than others. In addition, as the distance from the defect increased, the output voltage of the sensors decreased by 7.32% on average. It was also confirmed that the attenuation rate according to the distance decreased as the input discharge amount increased. For the application of this new type sensor, PD electrode system was designed to simulate the void defect. Waveforms and PRPD patterns measured by the proposed PD sensors at DIV and 120% of DIV were the same as the results measured by MPD 600 based on IEC 60270. The proposed PD sensors can be installed on the inner wall of the transformer tank by coating its surfaces with a non-conductive material; therefore, it is possible to detect internal defects more effectively at a closer distance from the defect than the conventional sensors.

DSSC (dye-sensitized solar cell) is expected to be one of the next-generation photovoltaics because of its environment-friendly and low-cost properties. However, commercialization of DSSC is difficult because of the electrolyte leakage. We propose thermal curable base on silicon resin and apply a unit cell and large area (200×200 mm) dye-sensitized solar cell. The resin aimed at sealing of DSSC and gives a promising resolution for sealing of practical DSSC. In result, the photoelectric conversion efficiency of the unit cell and the module was 6.63% and 5.49%, respectively. In the durability test result, the photoelectric conversion efficiency of the module during 500, 1,000, 1,500 and 2,000 hours was 0.73%, 0.73%, 1.82% and 2.36% respectively. It was confirmed that the photoelectric conversion efficiency characteristics are constant. We have developed encapsulation material of thermal curing method excellent in chemical resistance. A sealing material was applied to the dye-sensitized solar cell and it solved the problem of durability the dye-sensitized solar cell. Sealing material may be applied to verify the possibility of practical application of the dye-sensitized solar cell.

In this paper, we designed and fabricated low cost imprinting process for micro patterning on FCCL (flexible copper clad laminate). Compared to conventional imprinting process, developed fabrication method processing imprint and UV photolithography step simultaneously and it does not require resin etch process and it can also reduce the fabrication cost and processing time. Based on proposed method, patterns with 10 ㎛ linewidth are fabricated on 180 ㎜ × 180 ㎜ FCCL. Compared to conventional methods using LDI (laser direct imaging) equipment that showed minimum line with 10 ∼ 20 ㎛, proposed method shows comparable pattern resolution with very competitive price and shorter processing time. In terms of mass production, it can be applied to fabrication of large-area low cost applications including FPCB.

In order to application for high voltage heavy electric equipments, epoxy/microsilica 60 wt%/nano layered silicate composites (EMNC_60) and epoxy/microsilica 65 wt%/nano layered silicate composites (EMNC_65) respectively was synthesized by our electric field dispersion method and the result was obtained completely dispersion state. Thermal properties such as glass transition temperature (Tg) and thermal expansion coefficient, and DMA characteristics were studied, and mechanical properties such as tensile and flexural tests were performed. AC electrical insulation strength was also tested. The study on thermal property, EMNC_65 was better than EMNC_60 and mechanical ,electrical properties much improved EMNC_60 compared with EMNC_65.

In order to develop electrical insulation materials, epoxy-nanosilica-microsilica mixture composites (ENMC) was synthesized, and mechanical properties such as their tensile and flexural strength, and AC insulation breakdown strength were investigated. Properties of mechanical strength and AC insulation breakdown strength are analyzed as scale and shape parameter with respect to weibull plot. Their tensile and flexural strength, AC insulation breakdown strength were compared original epoxy or EMC to ENMC. The 4 phr nano-silica addition and the 65 wt% micron-silica mixture composite (ENMC) was found to have the highest tensile and flexural strength. In the tensile strength was improved 29%, and flexural strength was improved 60.9% higher than those of the original epoxy. In the insulation breakdown strength, ENMC_4 phr was improved 17% and ENMC_5 phr was improved 15.8% higher than those of the EMC.

This paper dealt with a partial discharge (PD) detection method for insulation diagnosis in cast-resin transformers. To detect PD pulse, a planar-capacitive probe was designed and fabricated. The probe has no insulation problem and can be installed on cast-resin transformers even in operation since it does not connect with high voltage conductor. The PD measurement system consists of the capacitive probe, a coupling network of 100 [kHz] low-cutoff frequency, and an amplifier with a gain of 40 [dB] and a frequency bandwidth of 500 [Hz]∼45 [MHz]. A plane-needle and a plane-plane electrode system were fabricated to simulate insulation defects in a cast-resin transformer. Sensitivity of the PD measurement system, which is evaluated by a standard calibrator was 0.35 [mV/pC] for positive and 0.45 [mV/pC] for negative, respectively. The PD detection by the capacitive probe was less sensitive than that by a coupling capacitor according to IEC 60270, but we could analyze the magnitude and the phase distribution of PD pulse.

Citations

• Machine Learning-Based Partial Discharge Recognition in Cast-resin transformers Using Phase-Synchronized Partial Discharge Detection Technique
  Gyeong-Yeol Lee, Gyung-Suk Kil
  Journal of Electrical Engineering & Technology.2026; 21(6): 5147.     CrossRef

Citations

• Improvement of Deposition Performance of Ultrasonic Spray Pyrolysis Deposition System through Atomizer Shape Modification
  Kyu-Eon Kim, Jae-Hoo Lee, Jae-Keon Jeon, Sung-Hwan Park, Chibum Lee
  Journal of The Korean Society of Manufacturing Technology Engineers.2015; 24(4): 469.     CrossRef
• Development of Control System for Ultrasonic Spray Pyrolysis Deposition
  Kyu-Eon Kim, Yeong-Heum Kim, Chibum Lee
  Journal of the Korean Society of Manufacturing Technology Engineers.2014; 23(4): 385.     CrossRef
• Fabrication of the Cu-STS-Cu Clad Metal for High Strength Electric Device Lead Frame and Thermal Stability on Their Physical Properties
  Il-Gwon Kim, Moon-Eui Son, Young-Sung Kim
  Journal of Welding and Joining.2014; 32(5): 80.     CrossRef
• Thermal Stability of the Mechanical and Thermal Conductive Properties on Cu-STS-Cu Clad Metal for LED Package Lead Frame
  Young-Sung Kim, Il-Gwon Kim
  Journal of the Korean Welding and Joining Society.2013; 31(5): 77.     CrossRef
• Study on the Mechanical Properties and Thermal Conductive Properties of Cu/STS/Cu Clad Metal for LED/semiconductor Package Device Lead Frame
  Chang-Hun Lee, Ki-Chul Kim, Young-Sung Kim
  Journal of Welding and Joining.2012; 30(3): 32.     CrossRef

Citations

• Nb-embedded Janus WSSe monolayer as a resistive or Schottky gas sensor upon CO, HCHO and C2H3Cl in dry transformers: a first-principles investigation
  Dan He, Guangming Li, Wen Cao, Hao Cui
  Physics Letters A.2025; 553: 130669.     CrossRef
• DFT simulations of Al-doped MoTe 2 monolayer as an HCHO and C 2 H 3 Cl gas sensor for status evaluation of a dry-type reactor in the HVDC converter station
  Pei Guo, Chao Xiao, Meng Yao, Yao Liu, Jing Hu, Jian Hu, Tai Li
  Molecular Physics.2025;[Epub]     CrossRef
• Fault signature gas sensing by the Ni-dispersed SnS 2 monolayer for operation status evaluation of dry-type transformer: a first-principles study
  Zhigang Chen, Chaoliang Qi, Xin Chen, YuZhe Bao, Yanan Yang, Fan Zhou
  Molecular Physics.2025;[Epub]     CrossRef
• Single Ni Atom-Dispersed WSe2 Monolayer for Sensing Typical Fault Gases in Dry-Type Transformers: A First-Principles Study
  Yan Liu, Jianben Liu, Zhuo Wei, Tian Yuan, Hao Cui
  ACS Omega.2023; 8(49): 47067.     CrossRef
• Implementation of Prediction Program for Deterioration Judgment on Substation Power Systems in Urban Railway
  Ho-Sung Jung, Young Park, Hyun-Il Kang
  The Transactions of The Korean Institute of Electrical Engineers.2013; 62(6): 881.     CrossRef